diff options
| author | Jakub Kicinski <jakub.kicinski@netronome.com> | 2019-03-29 17:08:53 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-04-29 08:29:21 +0200 |
| commit | b92e793bbe4a1c49dbf78d8d526561e7a7dd568a (patch) | |
| tree | 981f93f26cadc142d2b2280f1d9d8f60a9890e1c /kernel/jump_label.c | |
| parent | ad282a8117d5048398f506f20b092c14b3b3c43f (diff) | |
| download | linux-b92e793bbe4a1c49dbf78d8d526561e7a7dd568a.tar.gz linux-b92e793bbe4a1c49dbf78d8d526561e7a7dd568a.tar.bz2 linux-b92e793bbe4a1c49dbf78d8d526561e7a7dd568a.zip | |
locking/static_key: Factor out the fast path of static_key_slow_dec()
static_key_slow_dec() checks if the atomic enable count is larger
than 1, and if so there decrements it before taking the jump_label_lock.
Move this logic into a helper for reuse in rate limitted keys.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: alexei.starovoitov@gmail.com
Cc: ard.biesheuvel@linaro.org
Cc: oss-drivers@netronome.com
Cc: yamada.masahiro@socionext.com
Link: https://lkml.kernel.org/r/20190330000854.30142-3-jakub.kicinski@netronome.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/jump_label.c')
| -rw-r--r-- | kernel/jump_label.c | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 73bbbaddbd9c..02c3d11264dd 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -202,13 +202,13 @@ void static_key_disable(struct static_key *key) } EXPORT_SYMBOL_GPL(static_key_disable); -static void __static_key_slow_dec_cpuslocked(struct static_key *key, - unsigned long rate_limit, - struct delayed_work *work) +static bool static_key_slow_try_dec(struct static_key *key) { int val; - lockdep_assert_cpus_held(); + val = atomic_fetch_add_unless(&key->enabled, -1, 1); + if (val == 1) + return false; /* * The negative count check is valid even when a negative @@ -217,11 +217,18 @@ static void __static_key_slow_dec_cpuslocked(struct static_key *key, * returns is unbalanced, because all other static_key_slow_inc() * instances block while the update is in progress. */ - val = atomic_fetch_add_unless(&key->enabled, -1, 1); - if (val != 1) { - WARN(val < 0, "jump label: negative count!\n"); + WARN(val < 0, "jump label: negative count!\n"); + return true; +} + +static void __static_key_slow_dec_cpuslocked(struct static_key *key, + unsigned long rate_limit, + struct delayed_work *work) +{ + lockdep_assert_cpus_held(); + + if (static_key_slow_try_dec(key)) return; - } jump_label_lock(); if (atomic_dec_and_test(&key->enabled)) { |